Applicant claims priority under 35 USC 119 to German Patent Application No. DE 201 07 925.9 filed May 10, 2001.
The sport of kitesurfing has recently become established. Kitesurfing is a method of locomotion similar to surfing or waterskiing. A sportspersonxe2x80x94referred to as a kiteboarder or kitesurferxe2x80x94stands on a type of small surfboard on the water and is driven by a kite. The kite is held and steered by the kitesurfer by way of lines and stands at a height of approximately 10 to 50 meters above the water in the wind. At this height, the kite comes up against favorable winds. In this way, it is possible to achieve rapid movement similar to waterskiing.
The kite is a steering canopy similar to a paraglider or hang-glider, i.e. a flexible flying wing. Depending on the direction in which the kite is steered, it is possible to change the direction and strength of the pulling force of the kite. The force or pulling force of the kite always acts in the direction of the lines here. The kite is of aerofoil form, as a result of which it is possible to achieve an effective force in a direction perpendicular to the wind direction. It is thus also possible to tack against the wind, as with windsurfing equipment or a sailing boat.
It is generally the case that such kites are also suitable for driving sailing boats, ships or land-bound vehicles.
Two types of kites are basically known for kitesurfing, these being inflatable kites and soft kites.
An inflatable kite contains closed volume elements, chambers, which are inflated like a lilo, are closed by a plastic valve and keep the inflatable kite in the aerofoil form.
A soft kite does not contain any completely closed chambers. It comprises an upper sail and a lower sail which are adjacent to one another at a profile nose and a trailing profile edge. A soft kite also has at least one air-inlet opening in the lower sail with a respectively associated valve through which incoming air passes into the interior of the soft kite. Similarly to a paraglider, the soft kite automatically fills with air in the wind in order to achieve an aerofoil form.
Reference is made hereinbelow to FIG. 1, which shows a control bar 10 and the conventional lines for steering a kite.
The control bar 10 has a rubber coating so that it can be gripped in the hand without slipping even in wet and cold conditions. The control bar 10 has a harness line loop 20, with the aid of which the control bar 10 can be fitted into a hook on a kitesurfer""s harness, a corset-like vest like that used for windsurfing.
Two steering lines 12, 14 for the kite are fastened on the right and left on the outside of the control bar 10. The steering lines each act on the right-hand and left-hand wing ends of the kite. If one pulls, for example, on the right-hand steering line, then the kite tends to the right and flies through a right-hand curve.
Also provided is a depowering line 16 which acts on the front region of the kite and, upon actuation, pulls this down. The kite thus changes its angle of attack in the wind. It is positioned more flatly in the wind, as a result of which the force to which the kite is subjected in the wind is weaker. This results in the name xe2x80x9cdepowering linexe2x80x9d. The depowering line 16 is guided in the center of the control bar 10 and terminates in an annular loop, the so-called trim loop 18. The latter may be fitted into the hook of the harness. If the kitesurfer guides the control bar 10 away from his/her body because the pulling forces are becoming too great, the steering lines 12, 14 are released, but the depowering line 16 fastened on the harness is not. This results in a reduction in the lift to which the kite is subjected.
A common alternative to the depowering line is a brake line which pulls on the trailing profile edge and inflects the latter downward. This changes the profile shape and the flow around the kite can break away. In the case of pronounced pulling, the kite folds over and flies rearward in a pressureless state until it lands. Only a small amount of pulling is necessary, by way of a brake line, in order to start the kite from the water in the rearward direction.
Also usually provided is a safety leash which connects a steering line to the kitesurfer and is fastened, for example, on the kitesurfer""s arm or harness. The safety leash thus connects the kitesurfer and sail and/or control bar. The safety leash is normally loose and powerless. If, however, the kitesurfer loses the control bar and depowering line, he/she nevertheless remains connected to the control bar and kite via the safety leash. The only effective force is then a force to which that steering line on which the safety leash is fastened is subjected. The kite should then land as far as possible in a pressureless and controlled state. On account of the connection via the safety leash, it is possible to retrieve the control bar and kite.
Each kite should cover five elementary functions. These are: steering to the right, steering to the left, safety function, rearward flight/start-up and depowering. The known line systems, with four lines, only achieve four functions. The depowering line and brake line are never present simultaneously, and the operations of depowering and rearward start-up are thus never achieved at the same time.
A known line system for steering an inflatable kite 22 is illustrated schematically in FIG. 2. It has a left-hand steering line 12 and a right-hand steering line 14, which are fastened on the right and left on the outside of the control bar 10 held by the kitesurfer. They act on the trailing profile edge 15 approximately 2 m away from the wing ends. Also provided is a depowering line 24 which is guided centrally through the control bar 10 and can be fastened on the kitesurfer""s harness with the aid of a so-called trim loop 18. A short distance above the control bar 10, the depowering line 24 divides into a left-hand depowering line 26 and a right-hand depowering line 28, which act on the profile nose 11 at the wing ends.
On the leading profile edge, in each case one deflecting device 30 is fastened directly at the left-hand and right-hand wing ends. Located between the left-hand depowering line 26 and the left-hand steering line 12 is a connecting line 32, which is guided over the deflecting device 30 in the manner of a block and tackle. The connecting line 32 acts on the left-hand depowering line 26 approximately 2.5 m beneath the point at which the depowering line is fastened on the kite. The other end of the connecting line 32 acts on the left-hand steering line 12 approximately 90 cm beneath the deflecting device 30. A corresponding connecting line 32 is located between the right-hand depowering line 28 and the right-hand steering line 14.
If the left-hand steering line 12 is pulled, then, via the connecting line 32, the left-hand wing end 13 is pulled downward on the trailing profile edge 15, albeit, on account of the deflection in the deflecting device 30, only by half the extent of the movement of the left-hand steering line 12. This increases the air resistance of the kite at the left-hand wing end. On the right-hand side, there is a reduction in the air resistance as a result of the release of the roller 30. The kite executes a left-hand curve. The steering lines, which pass directly to the trailing edge 15 of the kite, hang freely and are not utilized for steering purposes.
A corresponding result is achieved if the right-hand steering line 14 is pulled.
If the two steering lines 12, 14 are pulled by a few meters at the same time, then the steering lines, which are guided as far as the trailing profile edge 15, become taut. This makes it possible to increase the angle of attack of the kite and to fly or to start up the kite, e.g. from the water, in the rearward direction. As a result of the strength of the inflatable kite, the profile is thus not curved.
If the depowering line 24 is pulled, then, on the one hand, the profile nose 11 is pulled downward at the wing end 13. On the other hand, as a result of the connecting lines 32, the trailing profile edge 15 is also pulled downward at the wing ends 13, albeit, on account of the deflection in the deflecting device 30, only by half the extent of the movement of the depowering lines. The kite 11 thus obtains a shallower angle of attack in the wind. This reduces the forces acting on the kite. The kite is thus depowered.
In the case of this known line system, the lines control the angle of attack of the kite in the wind. Curvature of the profile is not envisaged. A safety function as a result of the trailing edge folding over is thus not provided. Depowering via the curvature of the kite is not possible either.
The object of the invention is to specify an improved line system for a kitesurfer to steer a kite.
This object is achieved by the invention according to the independent claim. Advantageous embodiments of the invention are characterized in the subclaims.
The line system according to the invention covers the five elementary functions with only three lines, as will be explained at a later stage in the text.
It is particularly advantageous to use such a line system for a soft kite since the kite is more deformable. It is also possible, however, to use the line system for an inflatable kite.
The invention is explained in more detail hereinbelow with reference to exemplary embodiments which are illustrated schematically in the figures. The same designations in the individual figures designate the same elements.